It is unknown why a marriage was arranged between the king of Sweden and Norway and a member of the House of Namur. In June 1334 king Magnus travelled from Norway to Namur to propose. They were engaged in Namur and Magnus returned to Sweden in the fall of 1334. Blanche left Namur in the fall of 1335 and the wedding took place in October or early November 1335, possibly at Bohus Castle. As a wedding gift Blanche received the province of Tunsberg in Norway and Lödöse in Sweden as fiefs; Tunsberg was exchanged in 1353 to Bohus, Marstrand, Elfsyssel, Rånrike and Borgarsyssel. Blanche's coronation took place in July 1336, possibly 22 July, in the Great Church in Stockholm.[1] She was accompanied to Sweden by an entourage which included her brothers Robert and Louis, who came to be in service of her spouse: it is known that Louis remained in the king's service as late as 1354.

Queen Blanche was known in Sweden as Blanka, the Swedish version of her name. After her coronation, she was given her own seal with the inscription: "Blanche, by the Grace of God Queen of Sweden, Norway and Scania",[2] in which she is depicted with a crown and holding a scepter: unusually for a married woman of that period, she did not cover her hair with a veil.[3]

The queen was described as wise and as an extraordinary beauty.[4] At this point, Sweden did not have an official capital, and queen Blanche accompanied the king in their travels between the royal residences. In 1345, her brothers Louis and Robert were made vassals of her spouse.

Blanche and Magnus had two sons, Eric and Haakon, plus at least three daughters who died as children. In 1343, it was agreed that the two kingdoms of Sweden and Norway should again be divided, and that their eldest son Eric should inherit Sweden and their second son Haakon Norway.[5] The same year, Haakon was invested as King of Norway at the age of three. At this occasion, the members of the Norwegian council guaranteed the right of Magnus to govern Norway during the minority of Haakon and to resist all attempts from Haakons' elder brother to take over Norway: they swore their promise not only to Magnus, but also to queen Blanche.[6] On 18 November 1343, the archbishops and bishops of Sweden swore an oath to assist queen Blanche in the case king Magnus died when prince Eric was still minor.[7]

The seal of Blanche of Namur as Queen

The future saint Bridget of Sweden served as magistra or Mistress of the Robes to the queen at an unknown period, and regularly socialized with the royal couple before she left Sweden for Rome in 1349, and Bridget left descriptions of them and their court.[8] In the will of the royal couple from 1 May 1346, they made large donations to Bridget's planned Vadstena Abbey and asked to be buried there.[9] Bridget, however, opposed to their burial in her convent, and describe the royal couple in a negative fashion. She accused queen Blanche of having been a negative influence on state affairs by discrediting capable advisers before the king; "She is a snake with the tongue of a harlot, the bile of dragons in her heart and the most bitter poison in her flesh. Therefore all her eggs became poisonous. Lucky are those who never experience their burden".[10] Bridget expressed great dislike over the fact that the king and queen decided to live in a marriage without intercourse after the queen's 7th pregnancy; she claims that this was the reason for the king's rumored homosexuality, that queen Blanche had been responsible when Magnus made his controversial favorite Bengt Algotsson, Duke of Finland, and that Algotsson was the lover of them both.[11]

In the 1350s, a crisis occurred because of the Black Death and the failed politics in the Baltic, followed by the division of the kingdom of Sweden and Norway when their second son Haakon VI of Norway was declared of legal majority and free from his father's regency, resulting in the end of the united kingdoms of Sweden and Norway. In 1356, the opposition supported their eldest son Eric in a rebellion against his parents, resulting in a mediation where king Magnus had to make Eric his co-ruler and divide Sweden between them. During this conflict, queen Blanche seems to have supported her spouse against their son.[12] When Eric and his spouse Beatrice of Bavaria died in 1359, Blanche was accused of having poisoned them, accusations that are however regarded to have been but a part of the propaganda against her.[13] It is now believed that they died from the plague.

From 1359, she seems to have resided in Tønsberg Castle in Norway. Tønsberg was a part of her dower lands, and she ruled the area as her dower. It appears that her finances were somewhat strained during these years.

On 9 April 1363, she and Magnus attended the wedding of their son Haakon with Margaret, daughter of Valdemar IV of Denmark in Copenhagen. Shortly after the wedding, Blanche fell ill and died. The cause of death and the place where she is buried is unknown.[14]

Queen Blanche is one of the most well-known of the Swedish/Norwegian medieval queens. Apparently, she was very politically and socially active and noticeable, not only as a queen, as many stories and songs were written about her.

In Sweden, Queen Blanche is also remembered for the song: "Rida rida ranka, hästen heter Blanka" ("Ride, ride on my knee, the horse is called Blanka"), which has influenced the famous historical painting by Albert Edelfelt of her and her son Haakon.